The present invention relates generally to angle of arrival measuring systems and, in particular, monopulse microwave systems having angle of arrival measuring capability.
Prior art antenna systems typically have a problem distinguishing between signals that are detected with the main beam and signals that are detected with a sidelobe, commonly known as angle of arrival ambiguity. Conventional monopulse radar tracking systems generate angle error signals, but do not use phase shifters to shift the antenna beam to resolve ambiguity of the angle error signals or increase the angle of arrival accuracy. Phased array systems and beamforming systems use phase shifters to phase shift the received signal. However, such systems are primarly arranged for steering a beam, not for increasing the angle of arrival accuracy or resolving ambiguity of the angle of arrival signals.
Accordingly, in order to overcome the limitations of conventional systems, it is a feature of the present invention to provide a method and apparatus for angle of arrival determination having broadband capability, that more precisely measures the angle of arrival of target returns signal, and that resolves sidelobe ambiguity.